


Beast on a Leash

by N_A_N_O



Series: BEAST [3]
Category: Granblue Fantasy (Video Game), 神撃のバハムート | Shingeki no Bahamut | Rage of Bahamut (Anime)
Genre: Alternate Universe - Demons, BDSM, Chastity Belt, Corsetry, Flogging, M/M, Nipple Clamps, Nipple Play, Orgasm Denial, Porn With Plot, Porn with Feelings, Praise Kink, Sex Toys, Spanking, Voidwing!Sandalphon, Voidwing!lucifer
Language: English
Status: Completed
Published: 2019-05-12
Updated: 2019-05-12
Packaged: 2020-03-01 13:26:02
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,037
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18801244
Author URL: https://archiveofourown.org/users/N_A_N_O/pseuds/N_A_N_O
Summary: Lucifer loves to discipline a naughty little devil.





	Beast on a Leash

**Author's Note:**

> Please mind the tags before reading. Characters may seem OOC in Granblue Fantasy, but it's Rage of Bahamut context.

 

_To trespass against the Almighty’s holy law, on your knees, serve the Horned One. You shall prostrate before his pedestal, worship Him. In return, He will pave your path with the pleasures of sin and debauchery._

And the _Brictom_ , a scarlet mark branded on his white skin, sealed Sandalphon’s engagement as Lucifer’s first concubine. He had died as an angel, struck by God’s wrath, and had ressucitated as a demon.

The seraph from Heaven was jealous of the Light. Lucifer had drawn his blade against the Almighty and raised the flag of rebellion. Banished from Heaven to Hell with his soldiers, Lucifer claimed his throne as the Demon King.

He wanted peace and order in his ranks, so he created a new society by himself. He named the nine circles and his generals, dictated new laws and customs. The fracture of the Sacred Halo and the Brictom were only formalities for Sandalphon to stay close to his beloved king.

Every demon knows rules are meant to be broken, and Lucifer loves to discipline a naughty little devil.

Sandalphon is kneeling on a metal rod, serving Lucifer a glass of wine. His legs shiver as he pours it in and hands it out. He can feel Lucifer’s cold gaze on him, but only his pointy golden boots are in his line of sight. A foot comes in close. The sharp tip from the shoe forces him to lift his chin, not unlike a dagger set under his throat. Blood red liquid swirls in the glass, Lucifer’s purple lips narrow as he gazes at it, his long white lashes low.

“Is the wine not to your liking, Your Majesty?” Sandalphon asks, the tremors in his legs increasing as the rod rocks under his kneecaps.

“It’s fine,” Lucifer hums and forces him to lift his chin and straighten his position even more.

The Demon King is hard to read. He can smile while torturing a foe and remain stoic at the sight of the carnage of his brethren. Only his words and actions hold some truth or, at least, a warning. Sandalphon swallows his spit. They’ve spent eons together, but Lucifer never ends surprising him.

“Don’t forget this is supposed to be a punishment,” Lucifer says, his tone icy. “Lower, pet.”

Sandalphon stifles a whine as he wills himself down. The cold steel grinds into his tibia and the sides of his knees. He could swear he hears his cartilage crunch, and pain shoots into his feet.

“You should be grateful I took upon myself to discipline you,” Lucifer says.

Sandalphon shakes his head, grimacing and jolting in his effort not to sway and fall.

“I couldn’t let what he said slip! Azazel’s the one who escalated the situation!”

Lucifer sighs, and he crosses his long legs, leaning his cheek against the back of his hand.

“Lower.”

Sandalphon curses under his breath. If this continues, he’ll be doing the splits! He's sure Lucifer would go that far.

A few minutes of silence stretch out as Lucifer finishes drinking his cup of wine while Sandalphon squirms and whimpers beneath him.

“Azazel’s tight principles are sometimes unrealistic,” Lucifer admits, “but Cerberus can speak up for herself. She doesn’t need a small male yapping at her place.”

Sandalphon keeps his head low and mouth shut. The empty glass clinks as Lucifer sets it onto the table, and he stretches out his hand. Sandalphon winces as he stands up on wobbly legs and sits down on the divan. 

Lucifer pulls Sandalphon’s legs onto his lap, eliciting a hiss as he pushes them down straight. Brown stockings hide whatever bruises cover his knees. Sandalphon reclines against an armrest, and groans as Lucifer stretches his legs back and forth to relax them.

His hands are warm as he kneads through the kinks and tensions, cold as he puts them on the knees. He didn’t lose his original healing abilities after he fell from Heaven, and still shines the same as bright.

Sandalphon stretches lazily and hums. He could heal by himself faster than any human, but he enjoys the tender attention. This isn’t so bad, he thinks, but the impression his punishment is far from over keeps him from mindlessly opening his mouth.

“It’s unheard of that His Majesty in person discipline a concubine for a mere argument with a General. It sounds like a pretext to spend time with me while we shouldn’t,” Sandalphon says.

Lucifer glances to the side and taps a claw on his lip as he reflects on their options. Azazel is his most popular General since he contributed in Bahamut's defeat. If word spread that the king and his concubine had met on the same day Sandalphon fought with Azazel, many would feel compelled to make justice themselves.

“Why not indulge my spouses with a recording to say your visit was a public service?” Lucifer offers.

The blood drains from Sandalphon’s face, and he coughs. The other concubines will tear him apart. It’s a fight for survival in the harem between rivals, even with all of his privileges and his private room. That bitch Belial almost had his throat twice with her spear. It will be war in the boudoir, wrath in the bath, nitroglycerin in the trash bin!

“Y-you haven’t done that with anyone else! It’s too great an honor!”

Lucifer weaves a hand through Sandalphon's brown hair and caresses a  curled horn, before nuzzling against him.

“Part of your duty is to keep peace and order in our ranks. With all we’ve lost to Bahamut and the Black Knights, the morale is at rock bottom. We need to encourage my concubines to spawn new warriors.”

Bullshit; Lucifer isn’t that considerate. He hasn’t cared about what anyone thinks about him since he corrupted half of Heaven. While it’s true Hell is barely recovering from several cataclysms and wars; everyone’s already fucking like weasels to cope with their losses.

Lucifer uses a weapon to convince him - his most tender smile. It reminds Sandalphon of their first kiss in the shade of the Tree of Knowledge. He had dropped his cup of coffee in shock, and the black stain spread on the white pebbles. Darkness propagated over all of Heaven not long after that.

Sandalphon lowers his eyes, face hot at the memory, and says “Anything for you, Your Majesty.”

“Let’s warm up a bit before we begin,” Lucifer says. “On your knees.”

Lucifer stands in front of a kneeling Sandalphon. He’s a behemoth with his six wings unfurled. They cast a menacing shadow, and Lucifer’s eyes glow golden as his expression hardens. He sets his hands on his hips and hunches over the puny little thing at his feet. The weight of his aura alone could crush someone if he wanted to. He’s not the type to raise his voice, but only Lord Satan compares to how intimidating he can get. Sandalphon prostrates, shivering.

“Do you understand why you’re here?” Lucifer asks, his tone so calm it’s eerie.

“Y-yes Your Majesty,” Sandalphon replies in a small voice.

“Do you know what torment awaits you?”

Sandalphon shakes his head and bites his lower lip.

“I’ll have to spank you until you cry, humiliate and desecrate you in a recording, and make you beg Azazel and me for forgiveness with a flogging. Everyone will see your lewd shameful face while I break that rebellious character of yours.”

A twisted grin spreads on Sandalphon’s blushing face.

“Azazel’s still a jerk, and I won’t apologize,” he says.

A smile curls on the sides of Lucifer’s purple lips. He grabs the naughty demon by the loop of his dog collar and yanks him up. Sandalphon’s feet dangle in the emptiness. Lucifer’s eyes are magnificent, as cold and hard as they are now.

Lucifer drags him to a divan, pulls him flat onto his lap, subduing his energetic attempts to wriggle out of his iron grip. He pushes Sandalphon’s long green sash up, exposing a black tail, his naked behind and the garter belt holding his stockings. A leather strap harnesses a flared pad between his ass cheeks. Sandalphon breathes in sharply and folds his wings flat against his back.

The first impact descends on him. Sandalphon hums and wriggles his ass as a provocation. At the second, his skin ripples. He jolts and gasps. Lucifer knows how to do this right, to let the sensations grow, irregular enough to surprise him each strike. As soon as he relaxes – whack! It prickles, it’s hot. His butt must be turning a pale pink now. Swat! He can feel the heat slowly spread to his thighs. He squirms, catches a pillow to hold under his chest.

Heat replaces warmth. It isn’t long before Sandalphon needs to shrink out of the spanking. The pleasurable glow of the beginning has gone up to his groin, but Lucifer’s far from done. The impacts, while more or less the same, become biting. Sandalphon digs his nails into the pillow, grits his teeth as his hips begin to buck.

The numb sensation the short pauses leave is almost pleasurable. Sandalphon rubs his front against Lucifer’s thighs after every strike. It isn’t enough pressure to please him but distracts him from the pain.

“Oh no you don’t,” Lucifer chuckles and slaps hard.

Sandalphon’s head jolts up, and he squeaks. Lucifer pushes him into a position he can’t rub against him anymore. Sandalphon wriggles and flails, attempts to crawl away. It’s as if he were being branded again, the punishing hand the lick of infernal fire dancing on his skin.

It ends once he’s whimpering and limp, his butt dark red and ass twitching. Sandalphon hisses but doesn’t move as Lucifer caresses the irritated skin. His palm is hot; he doesn’t intend to heal him just yet. Pain gives way to a constant low throb and prickling. The claws of Lucifer’s golden gauntlet trace around the shameful plug Sandalphon isn’t allowed to take out until he enables him to.

Lucifer pulls Sandalphon up against him and kisses his forehead. He lets Sandalphon set his head on his chest for a little while.

“You haven’t apologized, even during the spanking.”

“I won’t apologize,” Sandalphon repeats, daring a quick lick at Lucifer’s earlobe.

“You never learn… Get in place,” Lucifer says dryly.

Lucifer returns to his throne and sits down. A shrill crystalline sound reverberates in the large room. Three Demon Cores appear, crystals floating in the air around a dark centrum. Sandalphon’s thankful it isn’t another demon or goblin assisting them, just a small machine controlled by Lucifer’s will.

They have small mirrors inside. Five confused, disheveled and blushing reflections stare back at Sandalphon. He frowns. If only his appearance were a bit fiercer, tall and loud like Azazel, nobody would pick a fight with him. His angelic features have stayed as much as Lucifer’s, only a black arm and his noble red horns proof he’s not of their kin anymore.

“Explain what you did and show them the consequences,” Lucifer says, a book in his hand. It seems Sandalphon will be the main actor in this. It wouldn’t be a punishment otherwise.

Sandalphon lets out a strangled sound and coughs. It’s just a dumb machine; nobody can see this yet.

“I-I called Azazel a jerk, and Lucifer spanked me,” he mumbles, pouting.

He pulls his sash up, exposing his beaten buttocks and a leather chastity belt. His balls and dick are wrapped tightly in the thick fabric. He shudders at the heat of the core, almost a caress between his thighs. He spreads his legs a bit more and runs his fingers on his balls and the pad.

The camera focuses on Sandalphon alone and only he can see Lucifer. For the moment, the King seems unaffected, but he’s controlling everything. Maybe he can see through the core, ogling at Sandalphon from every lewd angle.

“Undress. Keep the undergarments, you exhibitionist,” Lucifer says with a wry smile; he saw that small provocation.

Sandalphon’s lips quiver as he undresses. He reveals a corset belt is cinching his waist, but his chest is bare. Nipple clamps are linked together by a golden chain. At the front, the chastity belt would have looked like regular underwear, if it weren’t harnessed and there weren’t a ring denying him an orgasm. He looks erect, but it’s only the fabric holding him in an uncomfortable, humiliating position.

Sandalphon lets out a long shaky breath. He glances at the camera and lowers his eyes, rubbing his thighs together. That degree of subjection and objectification is necessary for him not to go feral. His demonic instincts drive his actions. As long as he can tease Lucifer, he doesn’t feel the need to destroy the world. He shows off the belt’s restrictive shape by squeezing his thighs together.

“How long have you worn it today?” Lucifer asks.

“A-all day…”

“Even during that argument with Azazel?”

Sandalphon breathes in sharply and whips his face away from the camera. An invisible force pins his hands against his back.

“Bend down onto the divan’s head,” Lucifer says.

Sandalphon rests his chest on it and shudders. A core hovers in front of him, another in his back. The lens reflects him panting like a dog in heat. The harness holding his butt plug in place latches off. Something, heck, maybe the core, slowly pulls the plug out. He sighs in relief and jolts when a slimy liquid suddenly dribbles down his ass and thighs.

“Prepare yourself.”

Sandalphon twists and turns to push a finger in, then two, into his lubed hole. He spreads his legs wider, his pace slow, careful to give the camera an eyeful. It makes his hips tingle to know something is filming him so closely, that someone may fap to what he’s doing, desire him, imagine themselves touching him, penetrating him. As an angel, he had such a lack of self-esteem, he’d have been too mortified to do this. Now, he’s corrupted beyond saving, and proud of himself.

“That should be enough,” Lucifer says after a while.

Yes, it seems the king is watching through the cores. Sandalphon’s hips shake in anticipation.

A metal bead pushes at Sandalphon’s entrance. It slowly slips in. The camera must be giving the viewers the impression they are the ones fucking him. And a second. And a third. More. He gasps at every regular, delightful spread, drops of sweat running down his neck.

Sandalphon’s legs are shaking, and he feels so full, so wonderfully full, and they are rolling, rubbing at sensitive nerves. He groans, exerting every muscle on his gleaming back and legs to keep standing. His dick is stiff and erect, squeezed by the chastity belt.

“You can take that much?” Lucifer asks.

“Your Majesty’s cock is bigger than those puny things aligned,” Sandalphon says, starting to giggle to hold back from moaning like a whore. He still has a bit of pride. Lucifer sighs.

A bundle of leather straps cracks together. Sandalphon's arms lift, and he’s cuffed to chains dangling from the ceiling, arms over his head. Lucifer’s metallic heels click on the floor and stop right behind him. Sandalphon can’t twist around to look, but Lucifer’s hand settles over his stomach, and he can feel Lucifer’s hot breath against the back of his neck.

“You give me no other choice, running such a dirty mouth.”

“M-mercy – Aah!”

Lucifer flogs near to his entrance as if to nudge the beads inside of him. They rub against his sweet spot, push him through the extremes between pleasure and pain. Lucifer flogs his upper back, thighs, the sides of his abused ass cheeks, grazes his covered balls with powerful swings. It sounds and feels like hail is falling on him. Exertion tears run down Sandalphon’s face as he gasps and cries, dangling when his knees buckle.

“Apologize to Azazel!” Lucifer roars.

The flogger cracks as he swats the same spot three times in a rattling row. It is noisier than painful, but the sound awakens a deep, primal fear within Sandalphon. It’s as if thunder were rumbling around him, lighting about to strike and reduce him to ashes.

“Sh-shorryy, I’m soooo – aah! Sorry, Azaze-hhhhl-samaah!” Sandalphon says, drooling from how heavenly it feels to be entirely beset by Lucifer’s wrath.

Sandalphon’s twisted. He loves pain, he’s loved it ever since the Almighty obliterated his physical form. He’ll never forget the tear towards oblivion and the ecstasy of resurrection as a demon. Both were so painful at first that they blurred the lines between agony and release.

“Turn around,” Lucifer says.

A shaking Sandalphon turns around. The camera reflects a wet red ecstatic face. He’s shameless, and seeing himself in such a state only excites him more.

Out of the camera’s focus, Lucifer licks the corners of his lips, his cheeks dusted pink and eyes dark. Sandalphon sways and lolls his head to the side, awed by Lucifer’s beauty. His entire being belongs to his king.

The core momentarily shuts off. Lucifer keeps Sandalphon cuffed and dangling, but kisses his neck and caresses his scratched back.

“You’re doing so good! You’re beautiful with such a lewd face,” he hums, his hand running down a  thigh. He kisses Sandalphon’s cheek.  

Too stunned to say or do anything, Lucifer’s out of his reach again before he could react. The cores hum back to life.

“Show them how good you are at laying eggs.”

Sandalphon’s legs shake. “P-please, h-have mercy…”

Lucifer chuckles; that’s not their safe word. In truth, the Fallen Angel is begging for it.

Sandalphon lets the Core’s arm pull them out slowly. It squelches his stomach grumbles. He sobs, moaning at every bead squeezes out of his ass, the lubricant coating them making him look like a sopping wet incubus.

His tongue sticks out, and he rolls his head back, quaking and unable to come. It’s so slow it drives him insane, pulling them out and sometimes pushing one back in. It ends once he’s begging and crying for release.

“You may use your mouth to pleasure me,” Lucifer says.

Sandalphon lifts his head with difficulty. His eyes are glazed, face wet with tears. The chains let go, and he falls to his knees. He crawls zigzagging to the throne where Lucifer waits.

Lucifer pushes his belt and sash out of the way. Oh, dark Tower of Babylon, the corruptor of saints! Sandalphon’s seen it many times, but his jaw still drops, his mouth dry. A demon has no soul, but he’d sell it for that divine dick!

Lucifer slightly lifts his book to leave Sandalphon space but resumes reading. It’s mostly to keep out of the lense's focus. He looks up to the side for a second, seems to have an idea, and he says, “Open your mouth wide.”

Sandalphon obeys. A ring gag binds around his head.

“I’d hate for you to dislocate your jaw,” Lucifer whispers, covering a wry smile behind pages of Machiavel.

Oh, that twisted sense of humor! The king can allow himself to be that arrogant; it isn’t even a lie. The ring at least gets the lips out of the way... Kind of. It makes him look ridiculous, but that’s also part of the humiliation.

Sandalphon puts himself to work, finding it hard to suck Lucifer off properly with his mouth forced that wide open. He stretches his tongue out, but can only use its tip to poke at the head’s slit, moves his lips but honestly looks like a fish. Lucifer sniggers. The only way to do it right, Sandalphon concludes…

Sandalphon takes it down in one go. Lucifer flinches. His sideways peek from the book seems scandalised. Sandalphon can’t hold back grinning, but only his eyes crinkle.

He loves how it pushes at the bottom of his throat, how hot and honest it is, compared to how cool Lucifer is acting.

He licks the precum off the slit, feels the pulse as he whirls his long demon tongue around it. Sandalphon moans and hums and sucks it with passion. He rubs his thighs together but is unable to get the friction he needs. After a few minutes, Lucifer grabs his hair, fucks him down his mouth. A few shivering thrusts, and he releases.

“Spit,” Lucifer says, catching his breath.

The gag unstraps from Sandalphon’s head. He lets the bit he didn’t swallow run down his lips, showing off Lucifer’s cum on his hand. It’s a privilege to taste the king’s seed, so he laps everything off, sucks his fingers loudly.

“On my lap, but don’t face me.”

He sits on his lap, back turned to him. Lucifer tugs at the chains holding the chest clamps together. Sandalphon jolts.

“You are very sensitive here, aren’t you,” Lucifer asks, and cruelly flicks one.

All Sandalphon can do is grit his teeth and nod.

When Lucifer undoes the clamps, Sandalphon hisses and grimaces. His nipples are dark red and marked by the prolonged strain.

“Play with them,” Lucifer says.

Sandalphon wants Lucifer to nibble and suck at them, but they can’t record that. Tenderness in their relationship is a facet only Sandalphon is allowed to witness. This treatment is all a play for the harem, a domination scene to uphold Lucifer’s status, to arouse the concubines. So, he does, albeit awkwardly. He wets them, plucks and pulls at them, acting his pleasure up a bit to entertain his king.

Lucifer’s gaze is dark, penetrative. Even though they shouldn’t claim exclusivity, Lucifer doesn’t look like that at anyone else. He watches Sandalphon run his fingers on his chest, squeeze the soft little red buds with delight. Lucifer undoes the chastity belt’s straps but leaves the ring preventing Sandalphon from going over the edge. The core approaches Sandalphon’s erect and dripping cock.

“Pleasure yourself, and I’ll let you come when I want you to,” Lucifer coos into Sandalphon’s ear, and nibbles at it.

Sandalphon relaxes against Lucifer’s broad chest. He can feel Lucifer’s hard bulge against his entrance, just a layer of clothing away.

Lucifer slowly unbinds Sandalphon’s corset, his breath hitched. His melting façade reveals a starving beast. This time, the camera is filming them both, showing even the king’s pink face and lidded eyes. White eyelashes flutter, and he sighs.

“Do you want to fuck my coochie or my ass?” Sandalphon mewls, dropping all formality as he masturbates, Lucifer’s chin on his shoulder.

Lucifer’s nostrils flare, and he breathes in sharply before nudging one of his horns against Sandalphon’s.

“I’m a man, but I can give Lucifer some devil pussy when he wants to,” Sandalphon continues, panting as Lucifer starts rocking his hips, rubbing into his thighs.

Lucifer’s breaths are shaky, and even his ears have become pink. He’s going to pieces as those dirty words come out from the mouth of the Fallen Angel. Eons ago, Sandalphon found it hard to demand as much as a kiss. He had spread his wings, emancipated from shame, guilt, and the Almighty’s laws. It had taken him so much to free himself, and here is his magnificent creation in full abandon.

“Don’t worry; that magic is only for you, Lucifer my love, my beacon of light!”

Lucifer growls and claims his lips. The corset drops. Sandalphon twists back to reciprocate, dizzied and elated. The king is kissing him in front of the camera, for everyone to see! The Scarlet Mark is glowing on Sandalphon’s stomach. Lucifer runs a hand on it as their tongues entwine.

He hoists Sandalphon up and lets him sink onto his erect shaft. Entirely naked and exposed, fucked under the eye of the lens, Sandalphon moans. The ring unclasps and falls to the floor.

He’s free, every assault a step closer to the gates of release. He can see his lewd face in the lens, glowing with ecstasy as Lucifer thrusts him up to Etemenanki.

“You see this,” Lucifer says in between sharp breaths, addressing the core and caressing the mark as he would his pregnant woman’s stomach, “Sandalphon is my solace, my Eve, and he will carry my spawn. Whoever dares to harm him will burn on the flaming wheels of hell!”

Sandalphon screams in pleasure as finally, at last, his head rolls back in the throes of a tremulous orgasm.

**Author's Note:**

> You may react to this through emojis or text. Let's play!  
>  Yeehaw = 🤠  
>  Spank = ✋  
>  OUCH = 😢  
>  Sandy! = 🤪  
>  Lucifer! = 😈  
>  MOAR = 😍  
>  Double Kudos = ❤️
> 
> Lore includes headcanons for another fic I might write someday. This is the first time I write smut like this, and I want to thank my friend and Beta-reader for her precious feedback. It's a bonus to my long fic Heart of Clay, which doesn't contain such extreme smut or practices.


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